alright got some knocking coming from under the hood of the z. sounds louder as i pass 1500 rpm. and its coming from the top of the motor. also had the car on and got under it, but i didn't here anything from down below. so it can't be a spun bearing. at first i thought it was a bad pushrod, rocker, or even a lifter. so i checked to see if the pushrods were bent or the rockers were loose. everything was good; neither bent or loose or broken. so now i went ahead and pulled the heads thinking maybe even a valve was bent or something. heads (prc heads and springs) looked fine then decided to pull the lifters (comp lifters) out. the lifters looked ok, alittle worn but nothing big. decided to get some lifters anyway. when i put everything together and started the car, the knocking was gone. well once the car started warming up, the knocking came back. so the next thing i did was pull off the front accessories and check to see maybe if there was a loose bolt or something, again everything was in tact. now at this point i am very frustrated. i called tsp to see if i can send the heads to them to maybe check them out for me. so right now at this point iam going to send the heads to tsp and see what they tell me. another thing im going to try is change my coils and wires, i already changed out the spark plugs so its not that. also switch out injectors, i have 98" injectors on instead of the 2000" that came in my car. well thats my long *** situation. i really about had it with this car and ready to throw it off a cliff. if u guys have any ideas or help i would greatly appreciate it.

 

What's your oil pressure? Are you sure the o-ring on the oil pick up tube is OK?

 

my pressure at idle is at about 38 psi. then when i would drive it would go to about 44 psi. well i did recently put in a new oil pump. let me check out the o-ring. thanks for the idea. but do u really think that it would cause it to knock if the o-ring was alittle pinched or out of place? thanks shevrolayz28! and i know there are alot of threads on knock or ticking motors, but i've searched and tried to find a solution and again nothing. any other ideas would greatly be appreciated!

 

Are you sure it's not just regular old LS1 piston slap?

 

Your oil pressure is definitely on the low side and it sure could cause some ticking IMO. Especially if you're using bigass valve springs.

Normal hot oil pressure from what I've seen is 40 at idle and close to 60 as the engine revs.

Most of the time when you see low oil pressure on these car it is caused by worn or mispositioned pick up tube o-ring. That's probably all it is. Get a new one before you even take it apart. Take your time installing it, even the best wrenchers struggle sometimes.

Another thing to look into is valve spring preload and pushrod length. But I really think your oil pressure is what needs to be addressed.

I'm thinking that it was quiet initially when you put in the new lifters but because of the low oil pressure they colapsed a bit, under load, after the engine ran a while.

I'm not at all an expert but this is what I've learned from reading on here. Good luck and let us know how you make out.

 

rod bearing i have the same problem as you next thing i do rebuild the block it suck

 

damn! man, im hoping its not a rod bearing. i just rebuilt this motor not even a year ago (3rd motor so far). but why would the sound be coming from up top of the motor? if it was a bearing, wouldn't it be mainly coming from the bottom? damn, maybe im in denial. and i know its not just piston slap. i know what piston slap sounds like and this is definitely not. and i wouldn't think that my oil pressure is that low. i thought that oil psi was about normal? well i guess all there is to do is wait for tsp to send my heads back and change out the injectors and pick-up tube oil ring and put it all together. if it still knocking after i put it together, then i guess take everything out again and send it to a machine shop. i'll let u guys know what happens. thanks for the ideas.

damn this **** is getting too expensive.

 

so the o ring is diffrent from ls1 pump to an ls6 pump?

 

i wouldn't think so. cause i put in a ls6 oil pump with the same o ring. and didn't have any issues with it.